The active and reliable reduction of the circulation in the wake turbulences behind big commercial airplanes directly at a runway from which the airplane takes off or on which the airplane lands is of high interest to the operating companies and customers of airports as it allows for reducing the security-related minimum distance between two succeeding airplanes. Such a reduction means a more effective use of the runway and a time saving in airplane service. With continuously increasing air traffic and with a lot of airports already being close to their capacity limit, a local solution of the wake turbulence problem which increases with the weight and thus with the possible number of passengers of a commercial airplane would be an essential step in minimizing the dangers and cost of airport operation.
A method and a device for reducing the circulation of wake vortexes in the wake turbulence behind an airplane that takes off or lands are known from DE 10 2005 025 004 A1. Here, at the end of the respective runway, which is flown over by the airplane, air is sucked into the ground in two areas which are located opposing to each other across a vertical middle plane of the runway and which are at a distance to this runway middle plane, and the air is blown back out of the ground in two other areas, which are closer to the vertical middle plane of the runway. In this way, circulating airflows are generated on both sides of the vertical middle plane of the runway, whose circulation directions—on each side of the vertical middle plane of the runway—are opposite to the circulation directions of the wake vortexes of an airplane taking off from the runway or landing on the runway. As a result, the circumferential velocity at the outer circumference of the wake vortexes behind the airplane is changed, and spiral-shaped instabilities are induced in the wake vortexes. These spiral-shaped instabilities propagate along the core of the wake vortexes at a propagation velocity which is about 20% of the airplane velocity.
The known method and the known device are only working, if substantial amounts of air are sucked into the ground and blown back out of the ground, as only then a change in the circumferential velocity of the wake vortexes behind the airplane is caused, which is essential for inducing the desired spiral-shaped instabilities. Actually, a major part of the circulation of the wake vortexes has to be deviated. I.e. the airflow generated at the ground has to correspond to more than 50% of the circulation of the wing vortexes to be disturbed. As a result, ventilators of very high power are required to create the airflow disturbing the wake vortexes at the ground.
There is still a need of a method and a device which allow for actively and reliably disturbing wake turbulences behind big commercial airplanes at low effort.